Description: Direction by inclusion as used here implies sethood. (Contributed by Stefan O'Rear, 2-Apr-2015)
Ref | Expression | ||
---|---|---|---|
Assertion | ipodrscl | ⊢ ( ( toInc ‘ 𝐴 ) ∈ Dirset → 𝐴 ∈ V ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | isipodrs | ⊢ ( ( toInc ‘ 𝐴 ) ∈ Dirset ↔ ( 𝐴 ∈ V ∧ 𝐴 ≠ ∅ ∧ ∀ 𝑥 ∈ 𝐴 ∀ 𝑦 ∈ 𝐴 ∃ 𝑧 ∈ 𝐴 ( 𝑥 ∪ 𝑦 ) ⊆ 𝑧 ) ) | |
2 | 1 | simp1bi | ⊢ ( ( toInc ‘ 𝐴 ) ∈ Dirset → 𝐴 ∈ V ) |